In the construction field, silt fence is a synthetic material, about the weight of canvas and typically 60 inches wide, installed around construction sites, disturbed areas, and in ditches to retain silt while allowing water to slowly pass through. Approximately 45 inches to 54 inches remain above the ground supported by posts, and the balance is buried in the ground to prevent soil and debris from escaping under the silt fencing. Most installation procedures follow engineering specifications calling for a trench 12 inches deep and 6 inches wide with a lap of silt fence covering the bottom of the trench to be covered and compacted with soil.
Erosion control, including silt fence, is mandated on all federal projects and on many urban projects, both public and private. Millions of feet are installed each year. Traditionally, the silt fence has been installed with support for its vertical position provided only through rigid support stakes set into the ground at varying intervals. This traditional method of installation without the presence of continuous vertical support between stakes often results in the failure of the silt fence to maintain its integrity. A breach in the integrity of the silt fence allows silt to flow over, under, or through the fence resulting in a failure of the silt barrier. Increasingly, administrative agencies and private entities responsible for construction projects, whose nature demands silt fencing, are requiring that the flexible silt fences be supported by rigid backing as support between stakes as a way to maintain the silt fence more securely in a vertical position and thus to prevent breaches of the silt barrier.
Furthermore, the traditional method of installation of silt fencing relies almost exclusively upon the compaction of soil around the subsurface portion of the silt fencing to anchor the silt fence in place. Due to poor compaction methods employed, silt fences installed in this traditional manner can become easily unanchored, especially during large rainwater events. Thus, this traditional method of anchoring often results in breaches of the integrity of the base of silt fence. Increasingly, administrative agencies and private entities responsible for construction projects whose nature demands silt fencing are requiring that improved methods for anchoring the silt fencing be employed to more securely affix the silt fence and better protect it against erosion and resulting gaps at the bottom.
Contractors from all over the country, hands-on people and large companies knowledgeable in the art and part of the industry, have attempted to build a machine that installs silt fencing efficiently and effectively. None have designed a means to simultaneously install a rigid wire mesh backing that will provide the horizontal and vertical benefits desired. Currently, most contractors use a trenching machine to dig and excavate a 150 mm deep trench, after which they pound in steel posts, insert wire mesh into the trench and then attach fabric to the wire in the open trench. The wire/fabric combination is then uprighted and held in place by posts with a short lip of the fabric/mesh combination on the bottom of the trench for soil to rest on. The trench is then manually backfilled by pushing the excavated soil into the open trench with a blade on their machine.
There exists one design of a machine invention disclosed in the Carpenter patent (U.S. Pat. No. 5,915,878), whereby silt fencing in installed with a rope anchor in a trench sliced by the same invention, but it does not teach the simultaneous incorporation of the wire mesh support member in its installation claims and has a number of important design differences. Carpenter does not teach or contemplate the simultaneous installation of a relatively rigid backing member, including the wire mesh of the present application, and thus it fails to address the problem of support for silt fencing that is now being demanded and/or required. Furthermore, Carpenter specifically requires that large holes be drilled in its wheel, used to insert silt fencing into a trench, as a means to avoid bunching or gathering of the silt fence material during installation, whereas the introduction of the wire mesh backing in the present application configures the silt fence fabric to avoid drilling holes that could compromise the structural integrity of the wheel. The presence of holes in the wheel of the present application could cause the wire mesh to become entangled with the wheel and pull the wire mesh out of the ground. Carpenter also requires the use of static panels as a means to guide the silt fencing fabric to its proper position for insertion by the wheel in that invention. Carpenter also employs static panels to hold the soil that has been sliced back while its wheel rolls the fabric in the ground, then allowing the soil to collapse back against the fabric after it passes by the panels. These panels will not work with the wire mesh in the present application because the panels would cause the wire to bunch up and become entangled with the panels instead of flowing through them. Again, the introduction of the wire mesh backing in the present application configures the silt fence fabric to avoid the need for panels or other guides for the fencing during installation. Furthermore, the incorporation of crimped wire mesh into the subterranean fold of the silt fencing in the present application provides far stronger anchoring qualities than the rope anchor taught by Carpenter. Finally, the foot member in the present application automates the compaction of soil displaced through installation of the silt fencing, an element and process that is not taught in Carpenter. Many other examples of the prior art are referenced in the Carpenter patent.
Thus, the present application improves on the prior art by automating and mechanizing the simultaneous installation of a rigid support member for silt fencing, by providing superior anchoring for the silt fencing once installed and by automating and mechanizing the compaction of disturbed soil after installation of the silt fencing. These enhancements over the prior art reduce labor costs and improve the structural integrity of silt fencing, presenting a cost benefit to consumers and the public, as well as a reduction in silt pollution to the environment.